This invention relates to a method and apparatus for constructing concrete panels and for utilizing the concrete panels is subsequent construction.
More particularly, the invention relates to a method and apparatus for simplifying the construction of concrete panels to include openings through which rebar and concrete slurry are extended in order to anchor the panel in a trench at a construction site to form a wall.
In a further respect, the invention relates to a method and apparatus for constructing a wall with a concrete panel in order to reduce the risk that the panel will, after the wall is constructed, settle and break.
U.S. Pat. No. 4,290,246 to Hilsey describes a concrete panel which includes a rectangular opening formed through the lower portion of the panel. The size of the rectangular opening is substantial and is preferably more than one-half of the width of the concrete panel. The Hilsey panel is installed at a construction site by setting the lower portion of the panel in a trench. Rebar is placed in and extends through the rectangular opening. The trench is filled with concrete slurry such that the slurry fills the rectangular opening and surrounds the rebar in the rectangular opening. While the concrete panel described in the Hilsey patent has been successfully utilized in constructing sound walls for freeways, the Hilsey panel has disadvantages. First, the large rectangular opening formed in the lower portion of the panel structurally weakens the panel, making it dangerous to attempt to raise the panel off the ground from a horizontal orientation by simply lifting the top of the panel and pivoting the panel about the lower edge of the panel contacting the ground. Instead, the panel is held at four points (two points on the upper portion of the panel and two points on the lower portion of the panel) and is tilted from a horizontal to a vertical orientation. Second, during manufacture of the panel, forming the rectangular opening requires additional forms which must be emplaced prior to pouring the concrete which produces the panel. Once concrete is poured and hardens, these additional forms must be "knocked out" prior to moving the panel. Third, when the panel is being anchored in a trench by pouring wet concrete through the rectangular opening, care must be taken to completely fill the rectangular opening with concrete to minimize structural weaknesses in the panel. Fourth, if the panel settles, breakage can occur along the upper edge of the rectangular openings, producing structural weaknesses which may form cracks in the panel.